摘要
目的探索实现胃癌磁共振扩散加权成像(DWI)的技术因素,评价胃癌DWI的临床应用价值。方法扩散加权单次激发平面回波成像(SS-EPI)序列连续检查胃癌患者53例,其中前期17例进行ASSET-DWI成像方法研究,结合分次屏气多信号平均技术,以肿瘤显示、伪影分级、对比噪声比(CNR)为评价标准,比较有无ASSET及不同信号平均次数(NEX)与ASSET搭配所得DWI图像的质量,确定成像参数;利用确定序列对后续36例胃癌进行成像研究,确定胃癌及非癌胃壁的DWI影像学表现及ADC值范围。扩散敏感梯度取b=0、1000s/mm2。结果ASSET-DWI组较无ASSET组成像速度提高,相关伪影(磁敏感伪影、化学位移伪影及Ghost伪影)轻且图像基本无变形(P<0.01);分次屏气采集对ADC值计算无影响(P>0.05);分次屏气多信号平均(4NEX)采集,可基本消除ASSET相关伪影,具备良好的对比噪声比。胃癌癌肿在DWI图上表现为稳定的高信号,平均ADC值为(1.17±0.22)×10-3mm2/s,非癌胃壁表现为低信号,平均ADC值为(1.94±0.28)×10-3mm2/s,二者差异有统计学意义(P<0.01);以ADC值<1.46×10-3mm2/s作为判定胃癌的标准,敏感性97.0%,特异性90.9%。结论8通道体部相控阵线圈联合ASSET技术及分次屏气多信号平均采集,实现了胃癌高b值扩散加权成像;ADC值可作为胃癌诊断的辅助指标。
Objective To explore the technical feasibility of diffusion-weighted MR imaging （DWI） in gastric cancer （GC）, and evaluate its clinical use. Methods Fifty-three patients with GC were examined with single-shot echo planar imaging （SS-EPI） sequence at 1.5T. The image quality of ASSET-DWI combined with different number of excitations （NEXs） were evaluated in 17 cases to determine the imaging parameters, concerning to the tumor detectability, gradation of artifacts and contrast-to-noise ratio （CNR）. Then 36 cases were imaged with the determined sequence to get the apparent diffusion coefficient （ADC） values of GC and non-cancerous gastric wall. The b values were 0 and 1000 s/mm^2. Results The acquisition time of DWI was reduced after associating with ASSET, and the EPI-related artifacts and image distortion were slighter than that without ASSET （P〈0.01）. There was no influence of separate breath-holds on the ADCs meacurement （P〈 0.05）. Separate breath-holds with multi-NEX technique could eliminate the ASSET-related artifacts and get high CNR images. The GC appeared high signal on DWI with an ADC value of （1.17±0.22） × 10^-3 mm^2/s, which had statistical difference to the non-cancerous gastric wall [ADC = （1.94±0. 28） × 10^-3 mm^2/s]. Taking ADCs〈1. 46 × 10^-3 mm^2/s as a standard for the diagnosis of GC, the sensitivity is 97.0% and the specificity is 90.9%. Conclusion The diffusion-weighted MR imaging of GC was achieved through the combination of ASSET and separate breath-hold with multi-NEX technique. The ADC can be an accessorial index in the diagnosis of GC.
出处
《中国医学影像技术》
CSCD
北大核心
2005年第12期1830-1834,共5页
Chinese Journal of Medical Imaging Technology
关键词
胃肿瘤
磁共振成像
扩散加权成像
并行采集
Stomach neoplasms
Magnetic resonance imaging
Diffusion-weighted imaging
Parallel imaging
